1. Field of the Invention
The present invention relates to a resist pattern thickening material, which is applied over a resist pattern that is formed in manufacturing a semiconductor device and is capable of thickening the resist pattern, and which may form a fine space pattern that exceeds exposure limits of light sources of available exposure devices. The present invention also relates to a process for forming a resist pattern, a semiconductor device, and a process for manufacturing the semiconductor device that utilize the resist pattern thickening material respectively.
2. Description of the Related Art
Semiconductor integrated circuits are becoming more highly integrated, and LSIs and VLSIs are being put into practical use. Accompanying this trend, the wiring patterns extend to regions of 0.2 μm or less, and the smallest patterns extend to regions of 0.1 μm or less. A lithographic technique is extremely important in forming fine wiring patterns. In the lithographic technique, a substrate to be processed on which a thin film is formed, is coated by a resist film, is selectively exposed, and thereafter, is developed to thereby form a resist pattern. Dry etching is carried out by using the resist pattern as a mask, and thereafter, by removing the resist pattern, the desired pattern is obtained. In forming a fine wiring pattern utilizing the lithographic technique, it is necessary to make the light source of the exposure device be a short wavelength, as well as to develop resist materials which have high resolution and is suitable to the characteristics of the light source.
However, in order to make a light source of an exposure device be a short wavelength, it is necessary to improve the exposure device, which results in very high costs. Further, the development of new resist materials suitable for an exposure with light of short wavelength is not easy.
To overcome the above technical problems, there has been proposed a technique wherein a resist pattern formed of a conventional resist material is formed and thickened by using a resist pattern thickening material (hereinafter, the resist pattern thickening material being sometimes referred to as “resist swelling material”) capable of forming a fine space pattern. For instance, Japanese Patent Application Laid-Open (JP-A) No. 10-73927 discloses a technique called RELACS. According to the disclosure, resist patterns are formed by exposing a resist of positive resist or negative resist using KrF (krypton fluoride) excimer laser light of wavelength 248 nm which is deep ultraviolet light as the exposure light. Thereafter, by means of a water-soluble resin composition, a coated film is provided so as to cover the resist pattern. The coated film and the resist pattern are made to interact at the interface thereof using the residual acid within the material of the resist pattern, and the resist pattern is thickened (hereinafter, the thickening of the resist pattern being sometimes referred to as “swelling”). In this way, the distance between the resist patterns is shortened, and a fine space pattern is formed. Thereafter, a desired pattern (e.g. wiring pattern) having the same dimension as the space pattern is formed.
In the RELACS technique, however, there is the following problems. The KrF resist for use is formed of an aromatic resin composition including a novolak resin, naphthoquinonediazide resin or the like. An aromatic ring contained in the aromatic resin composition allows KrF excimer laser light (wavelength: 248 nm) to pass through, but absorbs ArF excimer laser light (wavelength: 193 nm) having a shorter wavelength than the KrF excimer laser light and does not allow the ArF excimer laser light to pass through. Therefore, when the KrF resist is used, ArF excimer laser light cannot be used as the exposure light, which makes it impossible to from a finer wiring pattern, etc. Moreover, there is a problem in the RELACS technique that the resist swelling material is effective for thickening or swelling the KrF resist but not for thickening or swelling the ArF resist. In addition, the resist swelling material has low etch resistance itself. Thus, when ArF resist pattern having low etch resistance is swelled, the same dimension as the swelled pattern cannot be patterned on the substrate to be processed. Furthermore, even if KrF resist having relatively satisfactory etch resistance is swelled, in such cases where etching condition is severe, where the KrF resist pattern is fine, where the resist film is thin, or the like, there is a problem that etching cannot be precisely carried out and pattern having the same dimension as the swelled pattern cannot be obtained.
From the standpoint of forming a fine wiring pattern, it is desirable to be able to use light of a shorter wavelength than KrF excimer laser light, e.g., ArF excimer laser light, as the light source of the exposure device. In case x-ray or electron beam having a shorter wavelength than the ArF excimer laser light is used as exposure light of the resist to form the pattern, however, it results in high cost and low productivity. Thus, the utilization of ArF excimer laser light is desired.
As mentioned above, in the RELACS technique, the aforementioned resist swelling material does not efficiently work on ArF resist pattern. The present inventors have proposed a resist pattern thickening material capable of forming a fine pattern by improving affinity with the ArF resist pattern caused by a surfactant (JP-A No. 2003-131400). However, the composition of this resist pattern thickening material sometimes causes dependency on the pattern size before thickening, that is, when the pattern size before thickening increases, the reduced amount of the pattern size after thickening may increase in proportion to the increase. Thus, there was a problem that when the resist pattern thickening material was used for a line-space pattern, on a wiring layer of LOGIC LSI where various sizes of resist patterns are utilized, the burden on designing an exposure mask could not fully be alleviated.
Accordingly, the current situation is that there has not yet been developed a technique which can use ArF excimer laser light as the light source of an exposure device during patterning, which can sufficiently thicken ArF resist pattern or the like that cannot be thickened by using the aforementioned resist swelling material used in the RELACS technique, and which can easily form a fine space pattern or a wiring pattern at low cost. Therefore, it is desired that such technique be developed.
An object of the present invention is to provide a resist pattern thickening material, which can utilize ArF excimer laser light as exposure light during patterning; which, when applied over a resist pattern to be thickened, can efficiently thicken the resist pattern to be thickened, e.g., in form of lines and spaces pattern, regardless of the size of the resist pattern to be thickened; which has high etch resistance; and which is suited for forming a fine space pattern of resist, exceeding exposure limits or resolution limits of light sources of available exposure devices at low cost, easily and efficiently.
Another object of the present invention is to provide a process for forming a resist pattern which, during patterning a resist pattern to be thickened, can utilize ArF excimer laser light as a light source; which can thicken a resist pattern to be thickened, e.g., in form of lines and spaces pattern, regardless of the size of the resist pattern; and which is suited for forming a fine space pattern of resist, exceeding exposure limits or resolution limits of light sources of available exposure devices at low cost, easily and efficiently.
Yet another object of the present invention is to provide a process for manufacturing a semiconductor device in which, during patterning a resist pattern to be thickened, ArF excimer laser light can be utilized as a light source; a fine space pattern of resist, exceeding exposure limits or resolution limits of light sources of available exposure devices, can be formed; and high-performance semiconductor devices having fine wiring patterns formed by using the space pattern of resist can be efficiently mass produced, and is to provide a high-performance semiconductor which is manufactured by the process for manufacturing a semiconductor device and has fine wiring patterns.